<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .demo {
            width: 270px;
            height: 270px;
            line-height: 270px;
            background-color: #d9d9d9;
            border: 1px solid black;
            position: relative;
            top:232px;
            margin:auto;
            border-radius: 50%;
            animation-name: change;
            animation-duration: 2s;
            animation-iteration-count: 100;
            animation-timing-function: linear;
        }

        @keyframes change {
            0%{
                background-color: red;
            }

            50%{
                background-color: blue;
            }

            100%{
                background-color: yellow;
            }
        }
    </style>
</head>
<body>
<div class="demo">

</div>
</body>
</html>